SSQ1

Existing Annotations Review

GO Term	Evidence	Action	Reason
GO:0005737 cytoplasm	IBA GO_REF:0000033	ACCEPT	Summary: Cytoplasm includes the mitochondrial compartment in which Ssq1 acts. Reason: The actual Q05931 lineage descends from the cytoplasm IBD at PTN002321897, and matrix localization is independently supported by target studies. A broad, correct compartment is part of the core localization; it does not imply a separate soluble cytosolic pool. The more precise matrix annotation does not invalidate this ancestor. Propagation Review Root cause: NO FAILURE CORE Sources checked: PANTHER:PTN002321897 SUPPORTS TRANSFER Literal IBD and current root-to-Q05931 tree path verified; target SGD:S000004361 is among experimentally grounded descendants. Mitochondrial matrix is within cytoplasm. Supporting Evidence: PMID:10779357 The mitochondrial matrix of the yeast Saccharomyces cerevisiae contains two molecular chaperones of the Hsp70 class, Ssc1 and Ssq1.
GO:0005739 mitochondrion	IBA GO_REF:0000033	ACCEPT	Summary: Mitochondria are the core compartment of Ssq1-mediated Fe-S maturation. Reason: Ssq1 performs its established Fe-S transfer role in the mitochondrial matrix. The organelle parent represents that core location and is not downgraded because a matrix child term also exists. Propagation Review Root cause: NO FAILURE CORE Sources checked: PANTHER:PTN000452554 SUPPORTS TRANSFER The mitochondrial IBD is on the exact target lineage and includes target experimental grounding. Supporting Evidence: PMID:10779357 The mitochondrial matrix of the yeast Saccharomyces cerevisiae contains two molecular chaperones of the Hsp70 class, Ssc1 and Ssq1.
GO:0016887 ATP hydrolysis activity	IBA GO_REF:0000033	ACCEPT	Summary: ATP hydrolysis powers the specialized Ssq1 chaperone cycle. Reason: Full PMID:12756240 measures single-turnover ATP-to-ADP conversion and steady-state activity of purified Ssq1. Jac1 and Isu1 act cooperatively; Mge1 supports nucleotide release and cycling. These are direct catalytic measurements, independently supporting the family/mapping assertions. Propagation Review Root cause: NO FAILURE CORE Sources checked: PANTHER:PTN000452648 SUPPORTS TRANSFER Conserved Hsp70 ATPase IBD is an actual ancestor. Target SGD:S000004361 is valid experimental grounding, not circular support. Supporting Evidence: PMID:12756240 Jac1 and Isu1 cooperatively stimulate the ATPase activity of Ssq1.
GO:0031072 heat shock protein binding	IBA GO_REF:0000033	ACCEPT	Summary: Chaperone-system partner binding supports Ssq1 function. Reason: The ancestral heat-shock-protein interaction capacity is compatible with the functional chaperone system of Ssq1. Direct target biochemistry establishes nucleotide-sensitive interaction with the GrpE-family cochaperone Mge1 (PMID:11601843, PMID:12756240). This interaction resets the core ATPase cycle; specificity for Jac1 rather than Mdj1 does not imply loss of all ancestral chaperone interactions. Propagation Review Root cause: NO FAILURE CORE Sources checked: PANTHER:PTN000452648 SUPPORTS TRANSFER Actual ancestral interaction IBD verified. Core Mge1-dependent nucleotide cycling supports retention; no inference that every Hsp70 partner is interchangeable. Supporting Evidence: PMID:11601843 Ssq1 was able to form a specific complex with the nucleotide exchange factor Mge1.
GO:0044183 protein folding chaperone	IBA GO_REF:0000033	UNDECIDED	Summary: Folding assistance requires distinction from scaffold remodeling and aggregation suppression. Reason: The actual folding-chaperone IBD at PTN000452648 lies on the Ssq1 lineage, with no recorded NOT/IRD loss along that path. Target experiments establish an ATP-regulated client-binding cycle and antiaggregation capacity (PMID:11601843, PMID:12756240, PMID:16431909). Full PMID:16431909 Figure 4C measures rhodanese light scattering, not recovery of enzymatic activity; native Fe-S transfer does not automatically establish protein folding. Conversely, lack of Mdj1 stimulation in PMID:12756240 Figure 8 and client specialization do not refute every folding capacity. The previous automatic refinement to ATP-dependent protein folding chaperone was more specific than these assays establish. Focused adjudication is pending. Propagation Review Root cause: UNRESOLVED Sources checked: PANTHER:PTN000452648 UNRESOLVED IBD is on the exact current root-to-Q05931 path. Partner divergence is experimentally supported, but whether it removes the asserted folding function remains unresolved. Supporting Evidence: PMID:11601843 Ssq1 showed typical chaperone properties by binding to unfolded substrate proteins in an ATP-regulated manner. PMID:23615440 purified Ssq1 has been shown to be capable of protecting denatured rhodanese from aggregation in vitro
GO:0016226 iron-sulfur cluster assembly	IBA GO_REF:0000033	ACCEPT	Summary: Ssq1 directly contributes to the transfer stage of Fe-S cluster assembly. Reason: Ssq1 is an active chaperone participant: its ATPase cycle controls Isu binding and brings scaffold and Grx5 carrier together for cluster transfer. It need not synthesize the cluster chemically to participate in the assembly pathway. Full PMID:23615440 and PMID:12756240 provide target biochemical evidence for the inferred conserved process. Propagation Review Root cause: NO FAILURE CORE Sources checked: PANTHER:PTN000452554 SUPPORTS TRANSFER ISC IBD lies on the target lineage and includes target SGD:S000004361. Native transfer mechanism independently supports conservation. Supporting Evidence: PMID:23615440 The vicinity of Isu1 and Grx5 on the Hsp70 chaperone facilitates rapid Fe/S cluster transfer from Isu1 to Grx5. PMID:12756240 Jac1 and Isu1 cooperatively stimulate the ATPase activity of Ssq1. file:yeast/SSQ1/SSQ1-deep-research-falcon.md it promotes release of a newly assembled Fe–S cluster from the Isu scaffold
GO:0042026 protein refolding	IBA GO_REF:0000033	UNDECIDED	Summary: Retention of protein-refolding capacity remains unresolved. Reason: GO:0042026 requires restoration of biological activity of an unfolded or misfolded protein. The actual ancestral IBD is inherited along the Q05931 path without a recorded loss. Full PMID:16431909 demonstrates suppression of rhodanese aggregation but does not measure rhodanese reactivation; its Nfs1 effect can reflect prevention of unfolding and is dispensable for Nfs1 activity in mitochondrial lysates. Specific failure to use Mdj1 or to alter Yfh1 protease sensitivity (10779357) cannot establish universal loss. Therefore neither an unqualified refolding claim nor the previous categorical rejection follows from the inspected assays; a focused report is pending. Propagation Review Root cause: UNRESOLVED Sources checked: PANTHER:PTN000452648 UNRESOLVED Literal refolding IBD and target ancestry verified. No loss assertion on the path. Direct target assay interpretation remains unresolved rather than demonstrated functional divergence. Supporting Evidence: PMID:23615440 purified Ssq1 has been shown to be capable of protecting denatured rhodanese from aggregation in vitro PMID:11601843 Ssq1 showed typical chaperone properties by binding to unfolded substrate proteins in an ATP-regulated manner.
GO:0000166 nucleotide binding	IEA GO_REF:0000043	ACCEPT	Summary: Nucleotide binding is integral to the Ssq1 ATPase cycle. Reason: Full PMID:12756240 isolates Ssq1 bound to radiolabeled ATP, measures its conversion to ADP, and characterizes nucleotide release. A correct binding annotation is core even when a catalytic annotation gives additional information. Supporting Evidence: PMID:12756240 Jac1 and Isu1 cooperatively stimulate the ATPase activity of Ssq1.
GO:0005524 ATP binding	IEA GO_REF:0000120	ACCEPT	Summary: Atp binding is integral to the Ssq1 ATPase cycle. Reason: Full PMID:12756240 isolates Ssq1 bound to radiolabeled ATP, measures its conversion to ADP, and characterizes nucleotide release. A correct binding annotation is core even when a catalytic annotation gives additional information. Supporting Evidence: PMID:12756240 Jac1 and Isu1 cooperatively stimulate the ATPase activity of Ssq1.
GO:0005739 mitochondrion	IEA GO_REF:0000117	ACCEPT	Summary: Mitochondria are the core compartment of Ssq1-mediated Fe-S maturation. Reason: Ssq1 performs its established Fe-S transfer role in the mitochondrial matrix. The organelle parent represents that core location and is not downgraded because a matrix child term also exists. Supporting Evidence: PMID:10779357 The mitochondrial matrix of the yeast Saccharomyces cerevisiae contains two molecular chaperones of the Hsp70 class, Ssc1 and Ssq1.
GO:0005759 mitochondrial matrix	IEA GO_REF:0000044	ACCEPT	Summary: Ssq1 functions in the mitochondrial matrix. Reason: Target localization and organellar functional studies place Ssq1 in the matrix, where Isu, Jac1 and Grx5 cooperate in Fe-S maturation. PMID:8707841 used the historical SSH1 name for this Hsp70, also tracked in later Ssq1 literature; this should not be confused with the modern ER translocon gene sharing that old name. This location is supported positively and is not an exclusivity claim. Supporting Evidence: PMID:10779357 The mitochondrial matrix of the yeast Saccharomyces cerevisiae contains two molecular chaperones of the Hsp70 class, Ssc1 and Ssq1.
GO:0016787 hydrolase activity	IEA GO_REF:0000043	ACCEPT	Summary: Ssq1 is a hydrolase through its directly demonstrated ATPase activity. Reason: ATP hydrolysis is a hydrolytic reaction performed by Ssq1. GO:0016787 is broad but biologically correct and core; the more specific ATPase term does not justify a negative judgment on its ancestor. Supporting Evidence: PMID:12756240 Jac1 and Isu1 cooperatively stimulate the ATPase activity of Ssq1.
GO:0016887 ATP hydrolysis activity	IEA GO_REF:0000002	ACCEPT	Summary: ATP hydrolysis powers the specialized Ssq1 chaperone cycle. Reason: Full PMID:12756240 measures single-turnover ATP-to-ADP conversion and steady-state activity of purified Ssq1. Jac1 and Isu1 act cooperatively; Mge1 supports nucleotide release and cycling. These are direct catalytic measurements, independently supporting the family/mapping assertions. Supporting Evidence: PMID:12756240 Jac1 and Isu1 cooperatively stimulate the ATPase activity of Ssq1.
GO:0070013 intracellular organelle lumen	IEA GO_REF:0000117	ACCEPT	Summary: The mitochondrial matrix is an intracellular organelle lumen. Reason: The broad location follows from the experimentally supported matrix pool. Redundancy with a precise term is not evidence of over-annotation or a reason to classify the location as peripheral. Supporting Evidence: PMID:10779357 The mitochondrial matrix of the yeast Saccharomyces cerevisiae contains two molecular chaperones of the Hsp70 class, Ssc1 and Ssq1.
GO:0005515 protein binding	IPI PMID:12756240 Ssq1, a mitochondrial Hsp70 involved in iron-sulfur (Fe/S) c...	REMOVE	Summary: The reported Isu1 interaction is meaningful, but generic protein binding is uninformative. Reason: The full source directly measures Ssq1-Isu1 interaction by SPR and nucleotide-dependent glycerol-gradient association, with Jac1 promoting client engagement. Remove only this nonspecific molecular-function label under the protein-binding review policy, not the interaction evidence. Retain the established client-binding mechanism in the description, core function and references. A folding-specific replacement is not manufactured from binding alone while its functional scope remains under adjudication. Supporting Evidence: PMID:12756240 Isu, the proposed scaffold on which Fe/S centers are assembled, is a substrate for both Jac1 and Ssq1.
GO:0005515 protein binding	IPI PMID:12947415 An interaction between frataxin and Isu1/Nfs1 that is crucia...	REMOVE	Summary: The reported Isu1 interaction is meaningful, but generic protein binding is uninformative. Reason: The source reports Isu1-GST copurification and competition with native Isu1 supporting association with Ssq1; the source is about frataxin but also assays this interaction. Remove only this nonspecific molecular-function label under the protein-binding review policy, not the interaction evidence. Retain the established client-binding mechanism in the description, core function and references. A folding-specific replacement is not manufactured from binding alone while its functional scope remains under adjudication. Supporting Evidence: PMID:12756240 Isu, the proposed scaffold on which Fe/S centers are assembled, is a substrate for both Jac1 and Ssq1.
GO:0005515 protein binding	IPI PMID:16554755 Global landscape of protein complexes in the yeast Saccharom...	REMOVE	Summary: The Nop1-associated Ssq1 signal is real source evidence with unresolved physiological interpretation. Reason: Remove the uninformative generic protein-binding label while preserving the documented Nop1-bait TAP-MS association (PMID:19536198, Supplementary Table S2). This does not claim contamination or deny the interaction. Spoke inference and shared dataset lineage do not establish direct binary binding, a nuclear Ssq1 pool, or Nop1 folding, so no more specific replacement activity is proposed. Supporting Evidence: PMID:19536198 Interactions were assigned following a ‘spoke model'
GO:0005515 protein binding	IPI PMID:19536198 An atlas of chaperone-protein interactions in Saccharomyces ...	REMOVE	Summary: The Nop1-associated Ssq1 signal is real source evidence with unresolved physiological interpretation. Reason: Remove the uninformative generic protein-binding label while preserving the documented Nop1-bait TAP-MS association (PMID:19536198, Supplementary Table S2). This does not claim contamination or deny the interaction. Spoke inference and shared dataset lineage do not establish direct binary binding, a nuclear Ssq1 pool, or Nop1 folding, so no more specific replacement activity is proposed. Supporting Evidence: PMID:19536198 Interactions were assigned following a ‘spoke model'
GO:0005515 protein binding	IPI PMID:37968396 The social and structural architecture of the yeast protein ...	REMOVE	Summary: The reported Isu1 interaction is meaningful, but generic protein binding is uninformative. Reason: The source uses endogenous GFP pull-down/MS and reports an Isu1 interaction in the curated annotation; the specific supplementary interaction-score entry has not been independently rechecked. Remove only this nonspecific molecular-function label under the protein-binding review policy, not the interaction evidence. Retain the established client-binding mechanism in the description, core function and references. A folding-specific replacement is not manufactured from binding alone while its functional scope remains under adjudication. Supporting Evidence: PMID:12756240 Isu, the proposed scaffold on which Fe/S centers are assembled, is a substrate for both Jac1 and Ssq1.
GO:0016226 iron-sulfur cluster assembly	IMP PMID:11171977 Jac1, a mitochondrial J-type chaperone, is involved in the b...	ACCEPT	Summary: Ssq1 loss impairs Fe-S enzyme function independently of excess mitochondrial iron. Reason: The source PMID:11171977 explicitly tests ssq1 as well as jac1 mutants. Fe-S enzyme activities remain low when normal mitochondrial iron levels are maintained, supporting a biogenesis defect beyond secondary iron toxicity. The exact transfer-stage placement comes from additional biochemical studies, not an Isu-accumulation assay claimed for this paper. Supporting Evidence: PMID:11171977 Fe/S enzyme activities remain low in both jac1 and ssq1 mutant mitochondria even if normal mitochondrial iron levels are maintained. PMID:23615440 The vicinity of Isu1 and Grx5 on the Hsp70 chaperone facilitates rapid Fe/S cluster transfer from Isu1 to Grx5.
GO:0044571 [2Fe-2S] cluster assembly	IMP PMID:11273703 The mitochondrial proteins Ssq1 and Jac1 are required for th...	ACCEPT	Summary: Ssq1 contributes to maturation of [2Fe-2S] proteins. Reason: The source PMID:11273703 measures conversion of mitochondrial apoferredoxin to Fe-S-containing holoferredoxin and requires Ssq1 and Jac1. The native Isu-to-Grx5 transfer mechanism explains participation without assigning the initial cluster-synthesis chemistry to Ssq1. Supporting Evidence: PMID:11273703 Employing an assay that allowed us to monitor the conversion of the apoform of mitochondrial ferredoxin into its FeS-containing holoform, Ssq1 was demonstrated to be required for the FeS cluster assembly in mitochondria. PMID:23615440 The vicinity of Isu1 and Grx5 on the Hsp70 chaperone facilitates rapid Fe/S cluster transfer from Isu1 to Grx5.
GO:0005739 mitochondrion	IMP PMID:11273703 The mitochondrial proteins Ssq1 and Jac1 are required for th...	ACCEPT	Summary: Mitochondria are the core compartment of Ssq1-mediated Fe-S maturation. Reason: Ssq1 performs its established Fe-S transfer role in the mitochondrial matrix. The organelle parent represents that core location and is not downgraded because a matrix child term also exists. PMID:11273703 directly studies Ssq1-dependent holoferredoxin formation in isolated mitochondria. Supporting Evidence: PMID:10779357 The mitochondrial matrix of the yeast Saccharomyces cerevisiae contains two molecular chaperones of the Hsp70 class, Ssc1 and Ssq1.
GO:0006879 intracellular iron ion homeostasis	IMP PMID:9660806 Mt-Hsp70 homolog, Ssc2p, required for maturation of yeast fr...	KEEP AS NON CORE	Summary: Ssq1 dysfunction perturbs cellular iron homeostasis. Reason: The source PMID:9660806 explicitly identifies Ssc2p and reports increased cellular iron uptake and mitochondrial accumulation in mutants. This is a supported consequence of its Fe-S machinery role, retained as physiological context. It does not establish that Ssq1 itself transports iron or donates iron to a scaffold. Supporting Evidence: PMID:9660806 These mutants exhibit increased cellular iron uptake, and the iron accumulates exclusively within mitochondria.
GO:0016887 ATP hydrolysis activity	IDA PMID:12756240 Ssq1, a mitochondrial Hsp70 involved in iron-sulfur (Fe/S) c...	ACCEPT	Summary: ATP hydrolysis powers the specialized Ssq1 chaperone cycle. Reason: Full PMID:12756240 measures single-turnover ATP-to-ADP conversion and steady-state activity of purified Ssq1. Jac1 and Isu1 act cooperatively; Mge1 supports nucleotide release and cycling. These are direct catalytic measurements, independently supporting the family/mapping assertions. Supporting Evidence: PMID:12756240 Jac1 and Isu1 cooperatively stimulate the ATPase activity of Ssq1.
GO:0051082 unfolded protein binding	IDA PMID:11601843 The two mitochondrial heat shock proteins 70, Ssc1 and Ssq1,...	UNDECIDED	Summary: Unfolded-protein binding is established; its current functional replacement needs assay-level resolution. Reason: Live QuickGO confirms that GO:0051082 is obsolete, while the original source assertion is preserved. PMID:11601843 directly reports ATP-regulated unfolded-substrate binding. Full PMID:16431909 additionally shows aggregation suppression, particularly without ATP or with ADP. Neither observation alone establishes the ATP-driven folding outcome previously proposed as GO:0140662; the current holdase definition also includes prevention of aggregation and delivery to an acceptor or location. Select the replacement after focused assessment of the full binding assays and native client-remodeling mechanism, without declaring binding false. Supporting Evidence: PMID:11601843 Ssq1 showed typical chaperone properties by binding to unfolded substrate proteins in an ATP-regulated manner. PMID:23615440 purified Ssq1 has been shown to be capable of protecting denatured rhodanese from aggregation in vitro
GO:0005739 mitochondrion	HDA PMID:24769239 Quantitative variations of the mitochondrial proteome and ph...	ACCEPT	Summary: Mitochondria are the core compartment of Ssq1-mediated Fe-S maturation. Reason: Ssq1 performs its established Fe-S transfer role in the mitochondrial matrix. The organelle parent represents that core location and is not downgraded because a matrix child term also exists. The cited mitochondrial proteomics study is available as an abstract; its source-specific peptide entry was not independently rechecked. Retention also rests on independent target localization and organellar biochemistry, not on a claim that this abstract lists Ssq1. Supporting Evidence: PMID:10779357 The mitochondrial matrix of the yeast Saccharomyces cerevisiae contains two molecular chaperones of the Hsp70 class, Ssc1 and Ssq1.
GO:0005739 mitochondrion	HDA PMID:16823961 Toward the complete yeast mitochondrial proteome: multidimen...	ACCEPT	Summary: Mitochondria are the core compartment of Ssq1-mediated Fe-S maturation. Reason: Ssq1 performs its established Fe-S transfer role in the mitochondrial matrix. The organelle parent represents that core location and is not downgraded because a matrix child term also exists. The cited mitochondrial proteomics study is available as an abstract; its source-specific peptide entry was not independently rechecked. Retention also rests on independent target localization and organellar biochemistry, not on a claim that this abstract lists Ssq1. Supporting Evidence: PMID:10779357 The mitochondrial matrix of the yeast Saccharomyces cerevisiae contains two molecular chaperones of the Hsp70 class, Ssc1 and Ssq1.
GO:0005759 mitochondrial matrix	IDA PMID:8707841 The cold sensitivity of a mutant of Saccharomyces cerevisiae...	ACCEPT	Summary: Ssq1 functions in the mitochondrial matrix. Reason: Target localization and organellar functional studies place Ssq1 in the matrix, where Isu, Jac1 and Grx5 cooperate in Fe-S maturation. PMID:8707841 used the historical SSH1 name for this Hsp70, also tracked in later Ssq1 literature; this should not be confused with the modern ER translocon gene sharing that old name. This location is supported positively and is not an exclusivity claim. Supporting Evidence: PMID:10779357 The mitochondrial matrix of the yeast Saccharomyces cerevisiae contains two molecular chaperones of the Hsp70 class, Ssc1 and Ssq1.
GO:0016226 iron-sulfur cluster assembly	IMP PMID:9813017 Suppressors of superoxide dismutase (SOD1) deficiency in Sac...	ACCEPT	Summary: SSQ1 contributes to Fe-S cluster biogenesis. Reason: The source PMID:9813017 directly includes SSQ1 along with JAC1 and NFU1 and reports reduced activities of Fe-S enzymes in relevant null mutants. Later Ssq1 client-binding and transfer studies establish that the protein performs a chaperone step in the process, strengthening the original genetic inference. Supporting Evidence: PMID:23615440 The vicinity of Isu1 and Grx5 on the Hsp70 chaperone facilitates rapid Fe/S cluster transfer from Isu1 to Grx5.

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